Climate change is becoming the most significant global challenge and must be addressed on a global scale. At the time that this article is being written, the planetary heat in 2023 was the hottest on record. Similarly, the World Health Organization reports that 99% of the world's population lives in regions of unhealthy air pollution. Similarly, depression has become one of the leading causes of global mental and physical disabilities, and the impact of depression is predicted to only worsen over the next 25 years. It is interesting to note that climate experts often overlook the adoption of nutrition via a whole plant-based diet as a solution to both mental illness and climate change. In this review, we will touch upon the role of nutrition in gut microbiota and mental health, the impact diet has on greenhouse gases, the role of ultra-processed food, and environmental factors such as air pollution and increasing planetary heat and their growing impacts on mental health. In the end, the promotion of plant-based foods has the potential to improve personal mental and physical health while improving planetary health.